Flow system for paper formers



Jun 1964 D. E. ROBINSON ETAL 3,135,650

FLOW SYSTEM FOR PAPER FORMERS m Y N E 1 m0 N a MW. 4mm 9 T h BA N R 1 wl o A .w e m v s E M a 5 m 4 Y M B Filed Jan. 8, 1960 their June 2, 1954D. E. ROBINSON ETAL 3,135,650

FLOW SYSTEM FOR PAPER FORMERS Filed Jan. 8, 1960 3 Sheets-Sheet 2 IN VEN TORS i DAVID E. ROBINSON a BY JAMES MORAN 2 f 44 4 hi fiWg Mq [Ltheir ATTORNEYS.

J1me 1964 n. E. ROBINSON ETAL 3,135,650

FLOW SYSTEM FOR PAPER FORMERS FilGd Jan. 8, 1960 3 Sheets-Sheet 3INVENTO DAVID E. ROBINSO JAMES MORAN flown/du f, fiu fim vlmmd theirATTORNEYS United States Patent 3,135,650 FLDW SYSTEM FOR PAPER FORMERSDavid E. Robinson and James Moran, Norwalk, Conm, assignors to Time,Incorporated, New York, N.Y., a corporation of New York Filed Jan. 8,1960, Ser. No. 1,263 4 Claims. (Cl. 162-216) This invention relates to aflow system for delivering pulp furnish to a forming machine such as aFourdrinier or wet-end machine, and, more particularly, to a flow systemespecially designed to provide a pulp furnish of uniform consistency,having a uniform flow velocity or pressure face, to a forming machinefor the production of lightweight and uniform paper such as book paper.

In the formation of paper, it has been customary to use head boxes,extruders, and the like for depositing a layer of dilute pulp comprisedof fiber and water, the latter acting as a vehicle and bonding agent,upon a moving endless screen such as that of a Fourdrinier wire.However, because of flocculation of the pulp, cross currents, anduncontrolled and poor distribution of the fibers across the head box orextruder slice, non-uniform sheets having slice streaks and light anddark areas are produced. It is a fact of common knowledge that the sheetcannot be more uniform in consistency than the distribution of thefibers in the Water before drainage, and it is further apparent, thatthis non-uniformity on the slice streaks Will be especially noticeablein the production of light weight book paper. Pulp extruders and headboxes appear to be additionally unsatisfactory because of a non-uniformflow velocity or pressure face across the slice, also causing slicestreaks. In the case of head boxes, there may be provided holey rollsfor minimizing velocity variations, but such rolls have a number ofknown disadvantages.

It has been common with extruders and head boxes to utilize a shakemechanism connected to the Fourdrinier Wire in. the area adjacent theslice for the purpose of lightly vibrating or bouncing the stock in anattempt to even out the distribution of pulp and to eliminate slicestreaks. The advantages accruing from the use of shake is, however,out-weighed, particularly in the production of light Weight paper, bythe disadvantages resulting from disruption of the sheet during thisinitial forming stage.

It is also customary in present machines to position the head box orextruder slice above the wire and spaced therefrom whereby the stock ispermitted to drop a certain distance on the wire causing it to bouncethereon. This, however, has a tendency to cause a poor orientation ofthe fibers, a rough finish, and loss of dry strength in the formedsheet.

Thus, it is a primary object of the invention to provide a flow systemfor use in the manufacture of lightweight paper, and for depositing on aFourdrinier wire, or wetend machine, a pulp furnish of uniformconsistency and relatively free of flocs or the like.

It is also a primary object of the invention to provide a flow systemfor use in the manufacture of lightweight paper, depositing on aFourdrinier Wire, or wet-end machine, a pulp furnish or stock having auniform pressure face and a minimum variation in the velocity of thestock across the face of the slice.

In connection with the above objects, it is also a primary object toprovide a means for conditioning the pulp furnish with a high degree ofcontrol, and at the same time, obtaining sufiicient uniformity toeliminate the need and use of shake boards.

Also, it is an object of the invention to provide a means for extrudingpulp furnish tangentially on to a wire Without a vertical fall of thejet onto the wire.

A further object of the invention is to provide a flow Patented June 2,1964 system which may be used with existing forming equipment, wet-end,or Fourdrinier wire machines, and further which may be used on ahorizontal plane, or may be vertically oriented.

In accordance with the above mentioned objects, there is provided in theflow system a novel slice designed to discharge pulp furnish onto aFourdrinier wire, having upper and lower lips forming a rectangularcross-sectional slice area. To prevent any bounce of the stock on thewire, the slice is positioned above, but substantially adjacent to thewire, and adapted to extrude the pulp in the direction of travel and atapproximately the same speed as that of the wire.

The upper lip of the slice may be made pivotably adjustable with respectto its distance from the lower lip for controlling the thickness 'of theextruded stock upon the wire, and is also made to converge slightly onthe lower lip in the direction of travel of the flow to effect areduction in the velocity variation across the face of the slice. Theover all alteration in speed appears to effect an equalization of thepressure across the face of the flow.

. It is known with slice extruders to use a flow spreader or the likecomprising a number of parallel ducts positioned side by side andleading to the slice to distribute the pulp as evenly as possible acrossthe slice. In conventional spreader systems, however, the multiple ducttioned undesirable slice streaks. To reduce the non-uniformity of thevelocity pattern, or discontinuity in the pressure face, a novel flowcorrection chamber is positioned in the area intermediate the spreaderoutlets and the slice comprising essentially a box having flat andparallel top, bottom, and side walls forming a rectangular and elongatedcross-sectional area transverse to the direction of flow.

In one embodiment, the correction chamber may include a novel flowcorrector positioned in the chamber remote from the slice. The functionsof the flow corrector, in combination With the chamber and slice, are(l) .to further minimize velocity variations in the flow, (2)

to disperse and break up flocs of pulp fibers, (3) and to producecontrolled turbulence at the slice. The particular design of thecorrector should preferably be that capable of the most .correction ofthe flow causing the least amount of drag, and may comprise a shaped rodlocated transversely across the width of the chamber in front of theflow spreader: outlets, or alternatively, a series ofstackedspaced-apart corrector plates, or the like.

With respect to velocity correction, the variation in the flow velocityacross the face of the flow, at an over all velocity at about 2300 feetper minute, may be reduced from more than 20% at the spreader outlets toless than 1 /2 at the slice outlet by means of the combination of theslice and correction chamber, and by incorporating the corrector rod orflow correction means in the chamber, the variation in flow velocity maybe further reduced to from /2% variation to substantially no variation.

With respect to breaking up flocs, and fiber dispersion, the dimensionsof the components of the system are important. Generally, the height,width and length of the chamber and forward portion of the slice shouldbe gauged to the flow volume (in gallons per minute) and arranged tocreate sufficient turbulence, or to maintain the turbulence created bythe corrector rod, in a way adapted to keep the stock in a homogeneouscondition free of flocs. If the corrector rod is used, it may bedesirable to provide a length dimension sufiicient to permit excessiveturbulence to subside, or to even substantially reduce all turbulence toan almost frozen flow at the slice, if necessary. In any event, it isapparent that the present invention provides a novel combination ofelements which are capable of producing at the slice with a high degreeof control, practically any condition of the pulp desired. Generallyspeaking, the length should be the minimum necessary to produce thedesired result.

Although the slice, flow corrector, and spreader are illustrated asdesigned for use with a horizontal and flat paper former, it should benoted that they may be readily modified for a curved cylindrical formeror a vertical former if desired. Also, although the drawings indicatethe use of plastic in certain areas, many types of materials may be usedincluding stainless steel, particularly in areas requiring structuralrigidity. I

Generally, in operation, a pump provided in the flow line is set at thedesired volume of flow, which should produce a velocity sufficientlyhigh to prevent flocculation, and the wire speed is set to match theflow output from the slice. This fiow output is dependent on thethickness of stock desired and controlled by the spacing of the slicelips, and also on the design and width dimensions of the Fourdrinierwire, slice spreader and correction chamber. The wire speed may be setat from 100 to 107% of the flow speed.

A duct system which may be used with the present invention to conveypulp furnish from a storage vat, is described in copending application,Serial No. 1,262, entitled Flow Distributor, now Patent No. 3,076,502,and relates to a means for dividing the flow for distribution across theslice in a manner whereby equal amounts of ulp of equal consistency areobtained across the face of the slice. Although the present inventionmay be utilized successfully with any flow divider system, it hasparticular utility with that of the copending application in that thecombination presents a means for more accurately forming the paper sheetright at the slice in the correct consistency and uniformity to theextent that all that need be done with the pulp is to remove the waterfrom the sheet as rapidly as possible.

In a second copending application, Serial No. 1,261, entitled PaperFormer, there is.disclosed a wet-end machine having as principalobjectives those of forming paper of greater strength and having abetter finish. To accomplish this, it is proposed to provide a drainagesystem adapted to rapidly withdraw water from the sheet, and to set itimmediately after the stock is laid on the wire in the form as extrudedfrom the slice, and in a manner to prevent adverse disruption of thesheet. Since the flow system of the present invention provides a meansfor extruding from the slice a uniform layer of pulp furnish,particularly with respect to velocity of flow and pressure face, it hasparticular utility when combined with the above novel paper former.

Other objects and advantages of the invention will become apparent uponfurther consideration of the specification and accompanying drawings inwhich:

FIGURE 1 is a top plan view of a portion of a flow system according tothe present invention;

FIGURE 2 is a side view illustrating a flow system; according to theinvention;

FIGURE 3 is a side view of a flow divider as viewed along line 3-3 ofFIGURE 2;

FIGURE 4 is a view taken along line 44 of FIG- URE 1;

FIGURE 5 is a perspective view of a flow corrector;

FIGURES 6 and 7 illustrate additional embodiments of the flow corrector;and

FIGURE 8 illustrates a novel correction chamber assembly according tothe present invention.

Referring to, FIGURES 1 to 3, there is illustrated schematically a flowsystem designed in accordance with the principles of the presentinvention, comprising a storage vat 2, a standard Allis-Chalmers ACAPpump 4, a duct system 6 leading from the pump to a How divider section 8(FIGURES 2 and 3), multiple ducts 10 leading from the flow dividersection to a flow spreader or distributor 12 (FIGURES 2 and 1), a flowcorrection chamber 14, and slice 16. FIGURE 2 shows the relationship ofthe component parts of the flow system, and also illustrates theposition of the slice 16 with respect to a paper former breast roll 18.This figure also shows the position of a flow correction means 20 in thecorrection chamber 14 with respect to slice 16. In the describedembodiment of FIGURE 1, the flow spreader 12, iiow correction chamber 14and slice 16 are 18 in width, each of the ducts 22 of the flow spreaderbeing a rectangular duct 3" in width. Obviously the width of thecomponent parts, number of spreader ducts, and their combined width canbe greatly increased to accommodate for a much wider Fourdrinier wire.It will also be seen from further description of the correction chamberand spreader that multiple units can readily be joined to gether forthat purpose.

The slice, as shown in FIGURES 1 and 2, is comprised of an upper lip 24pivoting on means 26 attached to a correction chamber upper wall portion28, and lower lip 30 forming a substantially rectangular crossscctionalarea with means 32 for adjusting the spacing of the upper lip withrespect to the lower lip. The purpose of this adjustment is partly tocontrol the thickness of the extruded pulp layer, but also to facilitatein smoothing out velocity variations in fiow. The converging bottom andtop walls create a higher flow velocity and turbulence, both effectivein flow correction. The adjusting means 32 as illustrated in FIGURE 2,may comprise levers 34 and adjusting screws 36. The levers 34 areadapted for raising and lowering the whole upper lip together with theadjusting screws, and may be provided with an indicator to indicate thedistance of one lip from the other. The adjusting screws on the otherhand, are positioned at spaced intervals across the top of the upperlip, and not only brace the upper lip, but provide a means for creatinga wave therein. Thus, the distance between the upper and lower lips maybe varied across the face of the slice as desired. In operation, theslice is adjusted to give the desired thickness of the stock and theflow velocity is ascertained. The wire speed is then set to match it.For instance, in extrusion of about a A2" layer of stock the wire speedis adjusted to cause the flow of stock to be about 94% to of the speedof the wire.

The lower lip 30 as shown in FIGURE 2 is adapted in portion 38 toconform to the shape of the breast roll 18, and to be substantiallyadjacent to it and the wire 34, to avoid any fall and bouncing of thejet on the wire.

Immediately preceding the slice, there is positioned a flow correctionchamber 14, shown in FIGURE 1, comprised of a flow transformationportion 42 remote from the slice with the fiow corrector means 20positioned therein, and a portion 44 adjacent the slice 16. Essentiallythe whole chamber 14 comprises a rectangular box or the like having sidewalls 46 and flat and parallel bottom and top walls, 48 and 50, FIGURE2.

The flow transformation section is defined as that portion of the flowsystem where the flow from a multiple number of ducts is merged into asingle flow leading to the slice. FIGURES 1 and 4 show thetransformation section 42 of the correction chamber with multiple ducts22 of the fiow spreader 12 leading into it, and the resultant velocitypattern comprised of a number of extended velocity tongues V in linewith each outlet 52 of the flow spreader 12. The higher the velocity,the more pronounced the tongues, and thus the variation in the stockvelocity.

The flow corrector 20 may be positioned in front of the flow spreaderoutlets 52 transverse to the direction of flow of the stock and at apoint where it is estimated that the fiow from the spreader outlets 52has merged, which point may be from 4 to 6 inches in front I of theoutlets. At a flow velocity of about 2000 f.p.m., satisfactorycorrection of the flow has been obtained using a distance of about 4".This may be extended up to a distance of about 12" for a speed of 4000f.p.m. Actually in certain instances, it may be desirable to positionthe corrector much closer to the slice, and perhaps even relativelyadjacent to the slice opening.

The flow corrector 20, in embodiment shown in FIG- URE 5, is comprisedof a single circular rod 54 about /s" in diameter extending between theside walls 46 of the flow correction chamber, and held bystockflow-obstruction means such as the streamlined plate means, holderpieces or spacers 56 positioned between the bottom and top Walls 48 and50 of the correction chamber and along the apexes of the velocitytongues V, as shown in FIGURE 1.

A diameter of /8" appears to be satisfactory for speeds up to about 2400feet per minute, but for higher speeds, up to about 4000 feet perminute, a larger diameter may be useful. In this embodiment, the heightof the chamber is 1", and the slice narrows to about a opening. Each ofthe spreader duct outlets 52 are dimensioned at 1" x 3". All of thesedimensions may of course be varied.

The plate means corrector rod holders, in addition to supporting thecorrector rod, also have the important function of holding the boxtogether by the use of bolts extending through the walls and holes 58 ofthe holders. A large amount of internal pressure is experienced withinthe chamber in high velocity flow and thus the holders are of extremeimportance. It should be noted, that although the holders are positionedin front of each duct outlet 60, they are aerodynamically shaped andhave little elfect on the flow pattern.

Instead of using a cylindrical rod,the corrector may comprise a rodshaped in the form of a tear drop or wing having a rounded forwardsection and a pointed trailing section. Also, the corrector may have arectangular shape 60, as shown in FIGURE 6, or may be comprised ofseveral rods or plates 62 in a stacked relationship, as shown in FIGURE7. Surprisingly, the leading edge of the rectangular blades do notcollect fibers as might be expected. With respect to the FIGURE 6embodiment, the top and bottom surfaces may be made slightly divergingin the direction of flow, at an angle of about 20 with respect to eachother, forming an effective flow corrector. With respect to the FIGURE 7embodiment, any number of plates may be utilized, but the use of threestacked plates has been found to provide satisfactory results. Thesingle rod illustrated in FIGURE 5, however, as positioned anddescribed, seems to offer the best results.

The section 44 of the correction chamber adjacent the slice may be asshown, merely a continuation of the transformation section remote fromthe slice and containing the corrector rod. The critical feature,however, is its length and height which should be suflicient to allowthe eddies in the pulp furnish caused by the corrector rod tosubstantially subside if desired, or to be at a controlled level, andfurther to provide some additional flow correction. The minimum lengthrequired to do this is the preferred length.

Although, the top and bottom walls in the section 44 are spaced auniform distance apart, the chamber may be provided here with anexpansion area having bottom and top walls a variable distance apartcausing changes in the overall flow velocity. The purposes of such anexpansion chamber would be to again assist in eliminating variations inthe flow velocity pattern or pressure face. It is apparent that with anequal work input, and decrease in velocity there will be a greaterpressure differential created across the face of the flow and aresultant cross flow developed for pressure equalization. In thisrespect, however, it is important to avoid abrupt changes in thecross-sectional area which would likely cause vortices and flocculation.

The flow spreader or distributor outlets 52 leading into the flowcorrection chamber are preferably rectangular and adjacent each otherwith a minimum exposed surface in the portions 64 between the outletsdesigned to avoid the creation of vortices where the flow from the ductsis merged.

As indicated above, an important function of the corrector rod holdersor spacers is to hold together the bottom and top Walls of the pre-slicecorrection chamber or box against the internal pressures of the paperpulp. This function is even more critical at the flow speedscontemplated in the present invention. The conventional method ofwithstanding these high pressures consisted of using heavy externalbraces which braces made the entire device bulky and cumbersome and theelimination of them desirable.

The spacers illustrated in FIGURES 5, 6 and 7 having a rounded leadingedge or surface and a tapered trailing portion worked satisfactorily athigh flow speeds, but it was found that at low speeds of less than 1000to 1200 f.p.m. they had a tendency to load up with pulp on the leadingedge. An improved design of the spacers, suitable for all flow speeds,and one which will not load up, is illustrated in FIGURE 8. Essentially,it comprises stock-fioW-obstruction means such as a member 70 having aleading edge or surface consisting of a recessed center portion which isflat, rather than round and forwardly projecting bottom and top portions82 and 84, the latter being in contact with the bottom and top walls ofthe preslice chamber 14 at their leading-most edges. The surfacesbetween the fiat recessed area 80 and the leadingmost edges contactingthe bottom and top walls of the chamber are formed with a radius ofcurvature of about 7 of an inch for an inch high spacer. Theseleadingmost edges 82 and 84 are themselves provided with rounded corners86 and 88, rounded with about a A radius. The thickness of the spacer atits point of maximum width is about of an inch, and the distance betweenthe centers of curvature of the rounded corners 86 and 88 is about of aninch. By using a spacer dimensioned approximately proportional to theabove, pulp is prevented from loading up on the leading edge of thespacer, even at the points of contact between the spacer and the chamberwalls.

An assembly design for the spacer is also illustrated in FIG. 8comprising a multiple number of the spacers 70 positioned betweenparallel upper and lower horizontal plates 72 and 74-, and weldedthereto, thereby forming a compact replaceable unit. The spaced plates72 and 74 are in turn inserted in cooperating slots 76 and 78 formed inthe bottom and top walls 48 and 50 of the chamber 14. The slots 76 and78 are formed of a depth such that the inner surfaces of the plates 72and 74 will be flush with the inner surfaces of the chamber.

In addition to the functions already mentioned of the component parts ofthe fiow system, it should be noted that the system is also designed andconstructed throughout in a manner to prevent the creation of vortices,cross currents and the like which are principal causes of flocculationand slice streaks.

It is thus evident that the present invention provides an improved flowsystem for taking a stock flow from a multiple number of adjacent ductoutlets or from a flow spreader, and for substantially eliminating theinevitable but undesirable velocity tongues from the flow and producinga uniform pressure face in the flow prior to extrusion of the pulp fromthe slice. Cooperating to achieve these and other described results area novel flow correction chamber and fiow corrector positioned therein,

and a novel slice which in combination provide a pulp formation at theslice lips, where all that need be done is to remove the water as evenlyand as quickly as possible. Incidental to this, applicants thus providea means for forming a paper of better strength, consistency and finish.

It is to be understood that changes in details and materials may be madewithout departing from the spirit 'or scope of the invention. Forinstance, the correction chamber 14, which is illustrated as constructedof a plastic material may be instead constructed of rigid steel plates.Other modifications are within the scope of the appended claims.

We claim:

1. Apparatus for delivering a paper stock to a papermaking-machineslice, comprising a correction chamber adjacent to, communicating with,and upstream of said slice, a plurality of ducts adjacent to,communicating with and upstream of said correction chamber fordelivering to said correction chamber a paper stock under pressure,whereby paper stock passing from said ducts enters said correctionchamber with generally V-shaped velocity tongues, and a plurality ofstock-flow-obstruction plate means mounted within said correctionchamber and rigidly connecting spaced apart points on the interior wallsof said chamber to brace said chamber interiorly and reduce variationsin stock velocity across said slice.

2. Apparatus for delivering a paper stock to a papermaking-machineslice, comprising a correction chamber adjacent to, communicating with,and upstream of said slice, a plurality of ducts adjacent to,communicating with, and upstream of said correction chamber, wherebypaper stock passing from each of said ducts enters said correctionchamber with generally V-shaped velocity tongues, and a plurality ofstock-flow-obstruction means mounted 6 within said correction chamberalong the apexes of said velocity tongues, said correction chamberdefining, substantially unimpeded flow paths between saidstock-flowobstruction means.

3. A method of delivering a paper stock to a papermaking-machine slice,comprising the steps of forming a plurality of parallel streams of paperstock, passing said streams into a correction chamber, whereby saidstreams enter said correction chamber with generally V-shaped velocitytongues, obstructing said streams along the apexes of said velocitytongues, and providing relatively unimpeded flow paths through saidcorrection chamber between said apexes and to said slice.

4. A method of delivering a paper stock to a paperrnaking-machine slice,comprising the steps of forming a plurality of streams of paper stock,arranging said streams in a horizontal row, passing said streams into acorrection chamber, whereby said streams enter said correction chamberwith generally V-shaped velocity tongues, obstructing said streams invertical planes extending through the apexes of said velocity tongues,obstructing said streams in a horizontal plane extending through saidvelocity tongues, and providing, above and below said horizontal plane,substantially unimpeded flow paths between said vertical planes and tosaid slice.

References Cited in the file of this patent UNITED STATES PATENTS

3. A METHOD OF DELIVERING A PAPER STOCK TO A PAPERMAKING-MACHINE SLICE,COMPRISING OF THE STEPS OF FORMING A PLURALITY OF PARALLEL STREAMS OFPAPER STOCK, PASSING SAID STREAMS INTO A CORRECTION CHAMBER, WHEREBYSAID STREAMS ENTER SAID CORRECTION CHAMBER WITH GENERALLY V-SHAPEDVELOCITY TONGUES, OBSTRUCTING SAID STREAM ALONG THE APEXES OF SAIDVELOCITY TONGUES, AND PROVIDIG RELATIVELY UNIMPEDED FLOW PATHS THROUGHSAID CORRECTION CHAMBER BETWEEN SAID APEXES AND TO SAID SLICE.